Phytic acid–loaded Ce-based metal–organic frameworks enabling synergistic interfacial regulation for active/passive corrosion protection

Conventional epoxy coatings rely primarily on passive barrier effects and therefore lack the ability to regulate interfacial corrosion processes after local damage. Here, a physicochemically regulated active/passive epoxy coating is developed by incorporating a phytic acid–loaded cerium-based metal–organic framework (CeMOF-P) as a functional colloidal additive. Owing to the confinement and coordination effects of the CeMOF framework, phytic acid is stably immobilized and uniformly dispersed, resulting in improved coating compactness and interfacial adhesion. Electrochemical impedance spectroscopy shows that the CeMOF-P–modified coating exhibits markedly enhanced corrosion resistance and, more importantly, a characteristic non-monotonic impedance evolution with pronounced impedance recovery upon damage, indicating an interfacial regulation mechanism beyond passive shielding. Mechanistic analyses reveal that corrosion-triggered, coordinated release of Ce 3+ /Ce 4+ species and phytic acid leads to the in situ formation of a compact cerium–phosphate–rich interfacial film, which simultaneously suppresses anodic dissolution and cathodic reactions. These results demonstrate that Ce–P synergy enables continuous interfacial regulation rather than transient passivation, providing mechanistic insight into the role of coordination chemistry and colloidal confinement in governing interfacial electrochemical behavior and stability in protective coating systems.